import numpy as np
X=np.array([[51,55],[14,19],[0,4]])
print(X)
print(X[0])#访问X的第一个元素,第一个元素是一个数组
print(X[0][1])
for row in X:
    for i in row:
        print(i)
X=X.flatten() #将X转换为一维数组
print(X)       
print(X[np.array([0,2,4])])#X[[0,2,4]]
print(X[[0,2,4]]) 
print(X[::2])
print(X>15)
print(X[X>15])